package com.wangbo.collection;

import java.util.HashMap;

public class TestHashMap {
    public static void main(String[] args) {
        HashMap<Integer, Object> hashMap = new HashMap<>();
        hashMap.put(1, "hello");
        hashMap.put(2, 12L);
        test01(hashMap);
    }

    /**
     * keySet()
     */
    public static void test01(HashMap hashMap) {
        System.out.println(hashMap.keySet());
    }

}
